Processes hang in prune_dcache() when attempting to reclaim memory from dentry_cache

Issue

• Several processes appear to have a similar stack trace

    bpbkar        R  running task       0  6921      1          7417  6837 (NOTLB)
     ffff81017bbdbae8 0000000000000082 ffff810714d00780 ffff81063767e540
     ffff8105c23197a0 0000000000000001 ffff8105c23197a0 ffff810625e2e080
     00106019a96b16b8 0000000000003978 ffff8105c2319990 0000001780062ff8
    Call Trace:
     [<ffffffff8008e7fb>] __cond_resched+0x1c/0x44
     [<ffffffff8003b2c3>] cond_resched_lock+0x33/0x49
     [<ffffffff8002e7c4>] prune_dcache+0x2e/0x132
     [<ffffffff800ebd54>] shrink_dcache_memory+0x19/0x33
     [<ffffffff8003f46e>] shrink_slab+0xdc/0x153
     [<ffffffff800cba74>] try_to_free_pages+0x1da/0x2d7
     [<ffffffff8000f4b9>] __alloc_pages+0x1f8/0x308
     [<ffffffff8002e151>] __alloc_skb+0x77/0x12d
     [<ffffffff80026227>] tcp_sendmsg+0x564/0xb0b
     [<ffffffff80037c11>] do_sock_write+0xc6/0x102
     [<ffffffff80047604>] sock_aio_write+0x4f/0x5e
     [<ffffffff800182c3>] do_sync_write+0xc7/0x104
     [<ffffffff800a09d4>] autoremove_wake_function+0x0/0x2e
     [<ffffffff800325f9>] sys_faccessat+0xe4/0x18d
     [<ffffffff80016ab9>] vfs_write+0xe1/0x174
     [<ffffffff80017373>] sys_write+0x45/0x6e
     [<ffffffff8006149d>] sysenter_do_call+0x1e/0x76

• System hung in 100% system busy state